The present invention relates to a pump. More particularly this invention concerns a rotary pump of the canned type with magnetic coupling to a pump rotor.
A standard magnetically coupled can-type pump has a housing plate having a front face and a back face, a can fixed to the plate and defining a chamber on the back face thereof, and a bearing sleeve in the can fixed to the plate and extending rearward from the back face thereof along an axis. A rotor shaft extending axially through the sleeve is supported by bearings in the sleeve for rotation therein about the axis. An impeller is provided on a front end of the rotor shaft in a pump chamber at the front face of the housing plate. A rotor body fixed to a rear end of the shaft extends axially forward in the can around the bearing sleeve. It carries a plurality of permanent magnets that coact with another rotor or stator outside the can to rotate the impeller.
The rotor of the pump is therefore such that no electricity flows in it to create a shock hazard so that it can run wet. Thus the interior of the can is filled with the liquid being moved by the pump, for instance coolant water or lubricating oil. The rotor body is formed with one or more axially throughgoing passages and radially extending vanes are provided on the rear end of the rotor body. As the rotor spins, the vanes project fluid outward, pulling more axially in through the rotor body and thereby cooling and/or lubricating it and its bearings.
Such radial vanes have only limited pumping capacity at high pressure. Making them bigger, while it increases the volume of liquid moved, increases the amount of cavitation and the load on the rotor, decreasing pump efficiency. Furthermore the liquid is moved most forcibly between the rear end of the pump and the can, not in the central region of the body where such movement is most needed.
It is therefore an object of the present invention to provide an improved can-type pump.
Another object is the provision of such an improved can-type pump which overcomes the above-given disadvantages, that is which moves the liquid at a good rate through the center of the rotor so as to efficiently cool, flush, and lubricate it.
A pump has according to the invention a housing plate having a front face and a back face, a housing can fixed to the plate and defining a chamber on the back face thereof, a bearing sleeve in the can fixed to the plate and extending rearward from the back face thereof along an axis, and a rotor shaft extending axially through the sleeve and having a front end and a rear end. Bearings support the rotor shaft in the sleeve for rotation therein about the axis and an impeller is carried on the rotor-shaft front end in a pump chamber at the front face of the housing plate. A rotor body fixed to the shaft rear end extends axially forward in the can around the bearing sleeve. The rotor body defines an annular space around the bearing sleeve and is formed with at least one axially throughgoing passage open axially forward into the space and axially rearward into the can. In accordance with the invention a vane in the passage is angled for pumping liquid from inside the can axially forward into the space on rotation of the rotor about the axis.
The axially effective vanes are relatively close to the rotation axis of the rotation-symmetrical subassembly comprised of the shaft and rotor body. The vanes can be planar or curved and extend basically along planes forming angles of 5xc2x0 to 15xc2x0 with the rotor axis. Such vanes move a considerable volume of liquid with minimal cavitation, and direct the flow to the core of the rotor so as to drive it through the bearings and parts most needing lubrication and/or cooling. In fact the vanes can form the only connection between the rotor shaft, which can include a sleeve, and the rotor body, in which case the passage is annular, a plurality of the vanes are used, and they are angularly equispaced about the rotor axis. Since there are no vanes on the rear end of the rotor body, erosion of the inner face of the rear end of the can is reduced greatly. Overall the pump according to the invention will use less work to move more liquid than the prior-art systems.
The sleeve according to the invention has a rear end open into the space axially forward of the vane so that the liquid pumped by the vanes enters the rear end of the bearing sleeve and lubricates the bearings.
The rotor body carries magnets that cooperate with a magnetic rotor rotatable outside the can about the axis. In addition the bearings are ceramic. Thus whether oil or water is flowed through the rotor, the bearings will not be damaged and there will be no chance of a short circuit.
The plate according to the invention is formed with a passage communicating with an interior of the can forward of the rotor body and the pump chamber. In addition the rotor body is formed integrally with the vane and with a sleeve fixed to and snugly coaxially surrounding the shaft. The can is nonmagnetic and generally cylindrical.
The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing whose sole figure is a partly diagrammatic axial section through a pump according to the invention.